Overloading, abstract classes, and inheritance

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1 Overloading, abstract classes, and inheritance

2 Reusing this material This work is licensed under a Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International License. This means you are free to copy and redistribute the material and adapt and build on the material under the following terms: You must give appropriate credit, provide a link to the license and indicate if changes were made. If you adapt or build on the material you must distribute your work under the same license as the original. Note that this presentation may contain images owned by others. Please seek their permission before reusing these images.

3 Overloading Recall that generic interfaces can enable procedure overloading: module maths_functions interface my_sum module procedure real_sum module procedure int_sum end interface function real_sum (a, b) implicit none real, intent(in) :: a,b real_sum = a + b end function real_sum function int_sum (a, b) implicit none integer, intent(in) :: a,b int_sum = a + b end function int_sum end module

4 Overloading in F2003 generic keyword specifies polymorphism for type-bound procedure polymorphism without interface block Without this, type-bound procedures only resolve to a single method GENERIC [, access-spec ] :: generic-spec => binding-name1 [, binding-name2]... type maths_functions procedure real_sum procedure int_sum generic :: sum => real_sum, int_sum end type

5 Overloading generic-spec Interface statement: generic-name, must not be same as other type-binding operator (op) assignment (=) Allows for overloading of operators type maths_functions procedure real_sum procedure int_sum generic :: operator(+) => real_sum, int_sum end type

6 Inheritance Can extend types in F2003 type, extends(parent_type_name) :: child_type_name Inheritance specified via type extension Parent type is extended by child type Parent type may be a base type Child type has access to all component in base type (and ancestors) Child type can add new components New variables or procedures Includes implicit variable from parent class(es)

7 Inheritance example type person character(maxlen) :: name integer :: officenumber procedure, public :: getname procedure, public :: setname procedure, public :: getofficenumber procedure, public :: setofficenumber end type person type, extends(person) :: manager procedure, public :: addperson procedure, public :: removeperson procedure, public :: moveperson end type

8 Inheritance example type(manager) :: bob type(person) :: fred write(*,*) bob%getname() write(*,*) bob%person%getname() write(*,*) fred%getname() call bob%moveperson(fred,35) call fred%moveperson(bob,46)

9 Abstract classes Can define abstract classes and deferred procedures Define data Define procedures and interfaces Define implement procedures Define procedures to be implement by further classes Abstract class cannot be instantiated or allocated Can be used for class declaration in methods Important for type hierarchies

10 Abstract class example type, abstract :: individual character(maxlen) :: name integer :: officenumber procedure, non_overridable, public :: getname procedure, non_overridable, public :: setname procedure, non_overridable, public :: getofficenumber procedure, non_overridable, public :: setofficenumber procedure(printstuff), deferred :: print end type individual abstract interface subroutine printstuff(self) import :: individual class(individual), intent(in) :: self end subroutine printstuff end interface

11 Abstract class example type, extends(individual):: person procedure :: print => printperson end type person type, extends(person) :: manager procedure :: moveperson() end type manager

12 Summary F2003 allows derived types to extend other derived types Enables OO inheritance Abstract classes can be defined Enables interface/specification of code without requiring implementation Operators and procedures can be overloaded Same name used to call different procedures/operations based on the arguments passed

13 Exercise Extend your previous examples with operator overloading and class hierarchies (see the exercise sheet). Do the same for the percolate example.

Fortran classes and data visibility

Fortran classes and data visibility Reusing this material This work is licensed under a Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International License. http://creativecommons.org/licenses/by-ncsa/4.0/deed.en_us